The present invention relates in general terms to motor vehicle headlights, and in particular to a novel dipped beam headlight which is able to be adapted in an extremely simple way for driving on the right or for driving on the left.
Vehicle headlights of the elliptical type are well known in which the cut-off line of a dipped beam is defined by a mask or screen which is placed in the path of the light between a generally elliptical reflector and a convergent lens. In such a headlight, it has previously been proposed to make the form of the mask able to be modified selectively in such a way as to enable a beam to be produced respectively which is suitable for driving on the selected side of the road, i.e. on the right or on the left.
However, these arrangements are not able to be used in the case of a headlight in which the beam is formed directly by the reflector in cooperation with a light source (which may be partly masked). The above arrangements cannot be applied to a reflector of such a headlight, nor, where appropriate, to light-diverting elements such as striations or prisms formed on the cover glass of the headlight.
In this connection, in this type of headlight, one example of which is a light which uses a lamp of the xe2x80x9cH4xe2x80x9d normalised type in a parabolic reflector, the form of the reflector and/or the arrangement of the light-diverting elements is determinant to give a cut-off beam of good quality when driving on the required side of the road. In this connection, recourse to a so-called xe2x80x9cvacation maskxe2x80x9d, consisting of a band of opaque adhesive applied in an appropriate place on the front glass or lens of the headlight when the vehicle has to change its driving mode between the left and right hand sides of the road, is a palliative with which the modified beam is in no way satisfactory in terms of visual comfort. Thus, dipped beam headlights for driving on the left and for driving on the right must in general have reflective surfaces and/or front cover glasses (lenses) which are different from each other.
In addition, the Company Valeo Vision has developed, over the last few years, reflectors having reflective surfaces which are adapted to produce, by themselves, beams capable of being used both in traffic driving on the right and in traffic driving on the left, with the required photometry, in particular in terms of the cut-off line, homogeneity of the beam, and beam width. However, here again, the reflective surface is designed specifically for driving on a given side of the road, and a single surface is not suitable for use in common for driving on both the left and the right.
In addition, there is today a tendency to equip vehicle headlights with discharge lamps, which are well known for their substantially superior light intensity as compared with that of a filament light, but with a much smaller power consumption.
The high intensity of this type of light source, together with the presence, in the vicinity of the luminous arc itself, of secondary light sources which result from the accumulation of salts in certain regions of the lamp, or which result from reflections on the electrodes, do however pose particular problems, which are partly resolved by a design which is particular to the reflecting surface of the reflector itself.
Thus, the specific character of the reflective surfaces, related to their exclusive suitability for driving on either the left or the right, is often even more pronounced with this type of lamp.
One consequence of this exclusivity is the need to provide different mould parts for the two types of traffic, and (if necessary) also different designs of mould cavity, which does of course lead to high tooling costs.
In order to overcome the limitations in the state of the art as discussed above, it would be highly beneficial to design a headlight in which not only a common reflective surface, but also a common type of lamp, could be used for a headlight that would be adaptable so that by simply moving the lamp within the headlight, the setting of the latter could be changed from a setting suitable for driving on the left to a setting suitable for driving on the right. An object of the present invention is to satisfy this need.
Thus the present invention aims to provide a headlight which first of all has a reflective surface which is adapted to generate, according to the position of the lamp, a dipped beam for driving on the left and a dipped beam for driving on the right, and which also includes means, of particularly simple, inexpensive and reliable construction, for the purpose of ensuring suitable positioning of the lamp in its orientation corresponding to the required driving mode, i.e. on the right or left hand side of the road.
According to the invention, a motor vehicle headlight comprising a reflector and a lamp mounted in the said reflector is characterised in that the reflector has a reflective surface adapted to generate selectively two types of dipped beam, for driving on the left and driving on the right respectively, the reflector cooperating with a lamp occupying in a corresponding manner one of two given angular positions, in that the reflector carries a support member which is able to rotate with respect to the said reflector and on which the said lamp is mounted fixedly, and in that actuating means are provided for manually rotating the support member to one or the other of two working positions, each working position corresponding to a given one of the said angular positions of the lamp, together with locating means for locating the assembly that consists of the support member and the lamp on the one hand, and a fixed part of the headlight on the other hand, whereby to ensure stability of the position of the support member in each of the said working positions.
The support member preferably has a generally circular form and is guided in rotation by arrangements provided at the rear of the reflector.
Preferably, the headlight includes a single locking device, firstly for securing the lamp fixedly on the support member, and secondly for providing axial retention of the support member with respect to the reflector. The said locking means preferably consists of an elastic hairpin fastener or spring clip, in engagement against smooth zones of the cap of the lamp.
The actuating means for the support member preferably include a link which is articulated on the support member.
Preferably, the actuating means further include an articulated lever, pivoted on the said link and adapted to displace the said link.
The actuating means may comprise a screw-and-nut assembly, one of the elements (screw or nut) of which is fixed to the said link for straight line or axial movement with the said link. In that case, one of the elements comprising the screw or nut is preferably formed on a housing of the headlight.
Preferably, the above mentioned locating means comprise at least one finger fixed to the reflector and biased resiliently towards a notch defined on the lamp cap. There is preferably more than one of these locating fingers, and preferably, each locating finger has a rounded end, with the said notch having a width smaller than the width of each finger.
The locating means may consist of the screw and nut assembly, the end of travel positions of which are determined in such a way as to correspond to the two working positions of the support member.
The cooperation between threads of the screw and nut assembly preferably has substantially no axial clearance, and a predetermined minimal coefficient of friction.
Preferably, the lamp is a discharge lamp equipped with masking means. Alternatively, the lamp may be a lamp comprising at least one incandescent filament equipped with a mask of the cup type.
Further features and advantages of the invention will appear more clearly on a reading of the following detailed description of some preferred embodiments of the invention, which are given by way of non-limiting example only and with reference to the accompanying drawings.